During the temperate months of the year, the population of many pests in portions of the United States reaches levels which causes severe problems. One pest, the mosquito, can be distracting, can cause bites which itch and in certain cases can be a vector for the spread of communicable disease. Mosquito populations vary during the temperate periods of the year depending on rainfall, temperature, and other conditions. While the life span of an adult mosquito is not long, mosquito larvae can continually mature throughout the year into the adult stage, resulting in the continuing resupply of the mosquito population. Many communities have combatted mosquito populations by fogging or spraying the environment with insecticide, adding insecticide to likely hatching sites, and by distributing a variety of slow release insecticide compositions into the environment.
Many other pests can cause severe problems during the fair months of the year. Mollusks in both the adult and larval forms can infest fresh water, can damage flora and fauna, can be a disease vector, and can pose cosmetic problems. Fungi and algae can grow rapidly in fresh water and make water unpleasant for recreational purposes, can produce toxins which can poison farm animals and make water unfit for human consumption. A variety of plants can grow in unwanted areas reducing crop yields and presenting weed control problems in many residential and agricultural environments. Many attempts have been made to combat these pest problems using a variety of pesticides.
Pesticides have been encapsulated with both macro and microencapsulation processes in ceramic materials, biodegradable polymers, porous mineral supports, cellulose derivatives, polyurea compounds, gypsum and other supports in order to protect the insecticide from the environment and to insure a controlled release attempting substantial control of pest populations. I have had substantial experience with a number of these pesticide compositions and have found that they fail to provide one or more of the following properties. The pesticide must be released at a rate such that its concentration in the environment is maintained at at least an effective pest control concentration throughout the temperate part of the year in order to control pest populations at the time they appear. The pesticide should be released at an even rate such that significant amounts are not wasted. Pesticides should be protected from the effects of atmospheric oxidation, electromagnetic radiation (light energy or UV radiation) or other factors, which can cause the photochemical decomposition of the pesticide.
Accordingly a substantial need exists for a controlled slow release insecticide composition that can provide substantial control of pest populations throughout the temperate season, can provide a controlled continuous rate of release that maintains an effective mosquito controlling concentration of the insecticide in the environment, and which protects the insecticide from substantial degradation.